Brave sets the whole deal in motion (magic turns people into animals and all that). It’s also set in ancient times, so we’ll have from then until the present day for sentient, intelligent “people creatures” to interbreed with their new parent species and evolve a world where smart animals and insects are the norm (it wouldn’t happen that fast if at all, but hey, magic). Somewhere along the way, magic dies out and becomes relegated to superstition and folklore and people forget about a time when some creatures were just like us. The creatures themselves descend into hiding for the purposes of self-preservation.

Skip ahead to Ratatouille, and we see the animals tentatively poking out of hiding to test the waters, so to speak. The experiment seems to go well in the small, controlled environment of the movie, but it couldn’t be long before the idea of smart creatures ignites mass panic and some sort of cover-up on the part of the humans. The creatures go back into hiding, now a little more resentful of us. It’s also important to note here that while the creatures possess human-level intelligence, this movie establishes that they can’t communicate with us via speech.

Now we get to The Incredibles, as people begin to develop super powers. I’d put this further on, but the whole movie had a retro vibe to it, so it most likely took place before the events of Toy Story. Also, it introduces us to the first conceptual AI, which represents a massive leap in technological development and could then explain the sentient toys later on.

The Toy Story trilogy takes place simultaneously with A Bug’s Life and Finding Nemo, in the present day. In the trilogy, we see it well established that the AI programs have come to love humans and want us to be happy, while the creature movies clearly portray humans as apathetic antagonists at best. The battle lines are drawn.

Up could represent the final straw and the spark that would ignite the war. By developing a harness to allow communication with animals (who are already established as intelligent) it could be that the harness has the unintended side effect of essentially lobotomizing the creature, thus the relative stupidity of the dog when compared to, say, Ratatouille. However from the perspective of the humans, it would represent a HUGE step forward, so we would immediately set about harnessing every animal we could in an effort to communicate better. The creatures see this as nothing short of genocide, and they fight back. But as their presence become known, the AI machines rise up to protect us from the onslaught.

The first shots in the Machines vs. Monsters war are fired.

Now, even with the machines on our side, it’s pretty easy to believe that if every species of animal and insect simultaneously rose up against us, they’d wipe us out pretty quick, even with super heroes fighting with us. Hence the creation of the star ship that sends what remains of humanity into space to live happy and carefree lives, while the machines remain behind to deal with the monsters.

In the time it takes the machines to win the war, the monsters have continued to evolve. As they are pushed back further and further, they find a way to open a portal to a different dimension to escape, but not before swearing revenge against the humans somewhere down the road. So they dedicate their entire society in the new dimension to making technology powered by the screams of children in order to attack the humans while also perverting the technology that protected and saved them. They then use the portals to go back in time to before the War and harvest the screams of human children, hence Monsters Inc. The end of that movie could actually be seen as the legitimate end of the war, as the Monsters forget why they seem to hate us so much and focus on using laughter to gain energy instead.

Meanwhile, the machines win the ground war, and the cars emerge as the dominant machine race, ruling the planet until they screw everything up via pollution. This could start a civil war between them and the other machines, the aftermath of which leaves the planet in shambles, and the humans are completely forgotten in space until WALL-E finds them and brings them home.